Camellia yuhsienensis Hu, endemic to China, is a predominant oilseed crop, due to its high yield and pathogen resistance. Past studies have focused on the aboveground parts of C. yuhsienensis, whereas the microbial community of the rhizosphere has not been reported yet. This study is the first time to explore the influence of seasonal variation on the microbial community in the rhizosphere of C. yuhsienensis using high-throughput sequencing. The results showed that the dominant bacteria in the rhizosphere of C. yuhsienensis were Chloroflexi, Proteobacteria, Acidobacteria, Actinobacteria, and Planctomycetes, and the dominant fungi were Ascomycota, Basidiomycota, and Mucoromycota. Seasonal variation has significant effects on the abundance of the bacterial and fungal groups in the rhizosphere. A significant increase in bacterial abundance and diversity in the rhizosphere reflected the root activity of C. yuhsienensis in winter. Over the entire year, there were weak correlations between microorganisms and soil physiochemical properties in the rhizosphere. In this study, we found that the bacterial biomarkers in the rhizosphere were chemoorganotrophic Gram-negative bacteria that grow under aerobic conditions, and fungal biomarkers, such as Trichoderma, Mortierella, and Lecanicillium, exhibited protection against pathogens in the rhizosphere. In the rhizosphere of C. yuhsienensis, the dominant functions of the bacteria included nitrogen metabolism, oxidative phosphorylation, glycine, serine and threonine metabolism, glutathione metabolism, and sulfur metabolism. The dominant fungal functional groups were endophytes and ectomycorrhizal fungi of a symbiotroph trophic type. In conclusion, seasonal variation had a remarkable influence on the microbial communities and functions, which were also significantly different in the rhizosphere and non-rhizosphere of C. yuhsienensis. The rhizosphere of C. yuhsienensis provides suitable conditions with good air permeability that allows beneficial bacteria and fungi to dominate the soil microbial community, which can improve the growth and pathogen resistance of C. yuhsienensis.

Oil tea (Camellia spp.) is endemic to the hilly regions in the subtropics. Camellia yuhsienensis is resistant to diseases such as anthracnose and root rot, while Camellia oleifera is a high-yield species but susceptible to these diseases. We hypothesize that differences in the rhizosphere microbial communities and functions will elucidate the resistance mechanisms of these species. We used high-throughput sequencing over four seasons to characterize the rhizosphere microbiome of C. oleifera (Rhizo-Sus) and C. yuhsienensis (Rhizo-Res) and of the bulk soil control (BulkS). In Rhizo-Res, bacterial richness and diversity (Shannon index) in autumn and winter were both higher than that in Rhizo-Sus. In Rhizo-Res, fungal richness in autumn and winter and diversity in summer, autumn, and winter were higher than that in Rhizo-Sus. The seasonal variations in bacterial community structure were different, while that of fungal community structure were similar between Rhizo-Res and Rhizo-Sus. Gram-positive, facultatively anaerobic, and stress-tolerant bacteria were the dominant groups in Rhizo-Sus, while Gram-negative bacteria were the dominant group in Rhizo-Res. The significant differences in bacterial and fungal functions between Rhizo-Sus and Rhizo-Res were as follows: (1) in Rhizo-Sus, there were three bacterial and four fungal groups with plant growth promoting potentials, such as Brevibacterium epidermidis and Oidiodendron maius, and one bacterium and three fungi with pathogenic potentials, such as Gryllotalpicola sp. and Cyphellophora sessilis; (2) in Rhizo-Res, there were also three bacteria and four fungal groups with plant-growth-promoting potentials (e.g., Acinetobacter lwoffii and Cenococcum geophilum) but only one phytopathogen (Schizophyllum commune). In summary, the rhizosphere microbiome of disease-resistant C. yuhsienensis is characterized by a higher richness and diversity of microbial communities, more symbiotic fungal communities, and fewer pathogens compared to the rhizosphere of high-yield but disease-susceptible C. oleifera.

No abstract